Publisher Bridget Williams likes to quote British bookseller Tim Waterstone when asked what the future of books is.

"Anyone who tells you they know the future is telling you the most grotesque lie, because none of us do," Waterstone said.

The book industry - in both publishing and sales - is going through tough times.

And it is being felt acutely in the kind of publishing Bridget Williams Books (BWB) specialises in: local, intellectual books such as Max Rashbrooke's Inequality which caused a splash last year, focusing on this country's increasing divide between the haves and the have-nots; Claudia Orange's The Treaty of Waitangi, and Judith Binney's history books, though BWB also has some titles with more widespread appeal such as The New Zealand Pregnancy Book.

They are the kinds of book that tell local stories, but the economics of the industry have changed a great deal since BWB was founded in 1990 when Williams bought publisher Allen & Unwin's New Zealand business, which she had headed until its UK parent was sold that year.

Tight household budgets, the continuing rise of online sales driven by overseas companies, the spread of e-books and the globalisation of publishing and marketing have all had an impact on this "mid-list" area of publishing.

"People are buying fewer books," Williams says.

"It's partly recessionary factors. People are being more careful with their funds, and buying online is a major factor for all New Zealand retailers.

"A good NZ history that used to sell, say 3000-5000 copies is more likely now to sell 2000 or so."

That, she says, is "the great paradigm shift" that has taken place in publishing here.

The numbers indicate something of the issue. Although Booksellers NZ reports some independent bookshops have seen growth in the past year, the 2013 BookScan figures from researcher Nielsen show that volume of sales was 4.9 million through bookshops, or 15 per cent down on the previous year. Total sales were $115 million, Booksellers NZ said.

This does not include books bought GST-free through the likes of The Book Depository or Amazon, but those are not the places where the vast majority of locally-authored books are bought by New Zealanders.

Independent bookshops have been the great sales point for New Zealand titles, and the wave of closures which has diminished their numbers does not yet appear to have ended.

"I don't think we have seen the full flow-through of the seismic shift yet," Williams says.

Last year, Benny's in Taranaki and Chapters and Verses in Timaru shut up shop, she says.

That she is concerned about just two small, provincial booksellers closing is an illustration of their importance for local mid-list publishers such as BWB, Awa, and Bateman.

The lower sales of locally-authored books means most just don't make the cut for multinational publishers anymore, and they have slashed their New Zealand lists.

Williams says: "We have global publishing companies making increasingly global publishing decisions. Books that will sell worldwide, and in many thousands, are filling publishing lists now; books that we call in the trade 'midlist', or cultural publishing, are being increasingly pushed out, dropped, not signed."

That's not a peculiarly New Zealand thing. It's happening all over the world, but it is something the global success of Eleanor Catton's The Luminaries, an expansive novel set in historic Hokitika, rather obscures.

How does a publisher expect to get rich in such a market?

They don't, Williams says.

"In the past, an independent publishing company like BWB could make money, although probably we have all functioned more on a break-even rather than a highly profitable basis," she says.

"Today, the situation is very different, with sales falling significantly in some areas, and with a requirement also to invest in digital. So funding support is essential to what we do."

New Zealand's funding mechanisms are weaker than overseas, with Creative New Zealand focusing on funding fiction. Williams hopes some future culture minister will realise that should change.

"Historically, the small market is one of the reasons for state-funding for the development and publication of NZ content - just as the need for books expressing Canadian identity to counter powerful American influences was a reason for strong state-funding for writers and publishers in Canada over the years. Canada has a much better track record in this regard than New Zealand, however."

To cope with falling book sales and a dearth of non-fiction funding, BWB set up a publishing trust to help bring books to market with charitable funding.

It's just as well that Williams, who started her publishing career with Oxford University Press in the UK, thinks of herself as a publisher on a mission first, and a businesswoman second.

"I have to pay the bills, so yes, money is important. And being independent is important too. My primary interest is in doing good work - the kind of work I feel makes a contribution to this society."

BWB has brought a number of books to market seeking to help readers understand the economy and economic history. As well as Inequality, there have been histories of the liberalisation of the New Zealand economy such as Jane Kelsey's The New Zealand Experiment and her writings on the Trans-Pacific Partnership trade negotiations, as well as Cybele Locke's Workers at the Margins, about the loss of power of the working man.

These titles suggest what many would see as a centre-left ethos at BWB, but Williams isn't marketing to subsets of the population to confirm their world views. Rashbrooke was invited to present to PWC partners last year, indicating that the ideas in the book are of interest in even the most hard-nosed financial forums.

But the economics titles are selling just as badly as the more cultural titles.

"Take inequality," Williams says.

"[A few years ago] I would have expected to sell 5000 copies in six months, and perhaps look at another 3000-5000 in the next year because it is such a central issue, but we have sold well under 5000."

And this is a book that has been on the New Zealand bestseller lists since it was published.

Although the rise of the e-book has not produced vast new sales, and has brought new costs, Williams has embraced it. She wants the ideas BWB books contain to be available as widely as possible.

And there is always scope for innovation. BWB has begun publishing short e-books - BWB Texts - quick takes by authors and journalists on subjects such as asylum policies, the Christchurch earthquakes, as well as the personal experiences of luminaries such as scientist Sir Paul Callaghan.

Williams says: "They are short - which authors like and readers like. They're also great fun. We all enjoy thinking about them, having ideas, taking them to authors, having authors spring them on us."

Expect to see them in an independent bookshop near you.

"We're about to produce some of our Texts as small print books so we've started in digital and are shifting back to print with these ones."